Direct plant regeneration from different explants through micropropagation and determination of secondary metabolites in the critically endangered endemic Rhaponticoides mykalea

Direct plant regeneration from different explants, micropropagation and determination of secondary metabolites were studied in the critically endangered endemic Rhaponticoides mykalea (Hub.-Mor.) M.V. Agab & Greuter. Seed germination was achieved by damaging the seed coat and cultivating the embryos on Woody Plant Medium (WPM), of which 40% germinated. The epicotyls and cotyledonary petioles of seedlings were used as initial explants and direct shoot regeneration was obtained on WPM containing 2.22 μM 6-benzyladenine (BA). WPM medium supplemented with 2.22 μM BA and 4.92 μM indole-3-butyric acid (IBA) significantly improved the production of multiple shoots, resulting in an average of 5.6 shoots per explants. The highest rooting of shoots (35.6%) was observed with WPM medium containing 19.68 μM IBA with 990 μM putrescine. Plantlets with well-developed roots were transferred to soil and acclimatised within a plant growth chamber. Acclimatised plants showed 100% survival rate and remained healthy. As a part of our study, the content of secondary metabolites in three tissue culture regenerated lines were determined by HPLC analysis. Chlorogenic acid, Quercetin and scutellarin were confirmed secondary metabolites of R. mykalea.     

An approach to the chemosystematics of the zygophyllaceae

The Zygophyllaceae occur in arid zones and have been reported to contain, among other compounds, flavonoids and alkaloids. The flavonoids in representatives of three of the seven subfamilies have been studied and their distribution is discussed with respect to their chemosystematic significance. The aglycones identified were kaempferol, quercetin, isorhamnetin, herbacetin and herbacetin-8-O-methyl ether. Glycosidic patterns elucidated range from mono- to tri-glycosides, five of which are novel in plants. Alkaloids were also shown to be present, and the importance of those cited in the literature has been surveyed in relation to the chemosystematics of the Zygophyllaceae.     

A xanthone glycoside from Tripterospermum taiwanense and rutin from Gentiana flavo-maculata

Oleanolic acid, norathyriol, and a new xanthone glycoside, tripteroside, which was characterized as norathyriol 6-O-β-d-glucoside, were isolated from the fresh herb Tripterospermum taiwanense, and quercetin and rutin were isolated from the fresh herb Gentiana flavo-maculata.     

Preparation and in vitro and in vivo evaluation of quercetin-loaded mixed micelles for oral delivery

Quercetin (QT) is a plant polyphenol with various pharmacological properties. However, the low water solubility limits its therapeutic efficacy. In the present study, QT-loaded sodium taurocholate-Pluronic P123 (QT-loaded ST/P123) mixed micelles were developed and characterized, and the effect of the formulation on improving the water solubility of QT was investigated. QT-loaded ST/P123 mixed micelles were prepared by thin film hydration-direct dissolution and optimized by uniform design. The optimal formulation possessed high drug loading (12.6%) and entrapment efficiency (95.9%) in small (16.20 nm) spherically-shaped micelles. A low critical micelle concentration indicated that the micelles were stable, and they showed a sustained release pattern, as determined in vitro in simulated gastric fluid and intestinal fluid. Pharmacokinetic evaluation showed the C_max and AUC_0–24 were 1.8-fold and 1.6-fold higher than the QT suspension. The present results indicate that QT-loaded ST/P123 micelles are potential candidates to improve the solubility and oral bioavailability of QT.     

Leaf flavonoid patterns in Dipterocarpus and Hopea (Dipterocarpaceae)

In a flavonoid survey of five species ( D. alatus Roxb. & G.Don, D. costatus Gaertn. f., D. gracilis Blume, D. turbinatus Gaertn. f. and Hopea odorata Roxb . ) of Dipterocarpaceae from Bangladesh, three flavonoid aglycones and two glycosides were isolated. The flavonol kaempferol was detected in 40% of the total species surveyed, while the flavonol quercetin and flavone apigenin were present in all species examined, establishing their chemotaxonomic significance. Proanthocyanidins were found only in three species ( D. alatus , D. gracilis , D. turbinatus ), while the glycosides quercetin 3-glucoside and quercetin 3-rutinoside were isolated in 40% and 60% of the species surveyed, respectively. The flavonoid patterns of H. odorata and D. costatus are advanced in comparison to those of D. alatus , D. gracilis and D. turbinatus due to the loss of proanthocyanidin.  © 2003 The Linnean Society of London, Botanical Journal of the Linnean Society , 2003, 143 , 43−46.